A20B-3300-0602 Fanuc PCB Board A20B33000602 A2OB-33OO-O6O2

A20B-3300-0602 | FANUC 21i-B Pentium MMX CPU Module — 16MB DRAM / Upgraded Processor / Series 21i-B CNC / A20B-3300-060x Family

Pentium MMX — The Enhanced Pentium

The A20B-3300-060x family brings the Intel Pentium MMX processor to the FANUC Series 21i-B platform. The Pentium MMX is an enhanced revision of the standard Pentium, and its improvements deliver measurable benefits in the CNC environment:

Doubled L1 cache: The Pentium MMX expands the on-chip instruction cache from 8KB to 16KB and the data cache from 8KB to 16KB — twice the on-chip cache of the standard Pentium. With larger L1 cache, the processor satisfies more memory requests from on-chip storage rather than waiting for slower external DRAM. For CNC workloads — tight loops in servo coordination, PMC ladder execution, and display management — this translates directly to more instructions completed per clock cycle.

Improved branch prediction: The Pentium MMX's updated branch prediction unit better anticipates conditional jumps in code sequences. CNC software contains extensive conditional logic — mode checks, alarm condition evaluation, PMC ladder rung evaluation — all of which benefit from accurate branch prediction.

MMX instruction set: While the 57 MMX instructions target multimedia workloads (video, audio, 3D graphics), their SIMD (Single Instruction, Multiple Data) capability can be applied by FANUC's software engineers to parallelise certain calculation patterns in display rendering and look-ahead processing.

Key Specifications

A20B-3300-060x — Pentium MMX Family for the i-B Generation

The A20B-3300-060x family covers Pentium MMX modules for different i-B CNC platforms:

The 0602 and 0603 are the 21i-B specific variants within the 060x family. The distinction between them is memory capacity — 0602 at 16MB and 0603 at 32MB.

Both 0602 and 0603 represent an upgrade path from the earlier standard Pentium modules for the same 21i-B platform (A20B-3300-0312: Pentium 16MB for 21i-B). The Pentium MMX delivers the same 16i functionality with improved cache and branch prediction performance.

Application Scenarios

21i-B CPU module upgrade: A FANUC Series 21i-B CNC running an earlier standard Pentium module (A20B-3300-0312) is upgraded to the A20B-3300-0602 Pentium MMX module. The improved cache performance delivers faster block processing and more responsive display updates.

21i-B CPU module fault: A Series 21i-B CNC develops CPU-level boot failures. The A20B-3300-0602 Pentium MMX module is identified as the fault. Replacement restores the 21i-B CNC's processing function.

FAQ

Q1: What is the difference between A20B-3300-0602 (Pentium MMX 16MB) and A20B-3300-0312 (standard Pentium 16MB) for the 21i-B?

Both serve the Series 21i-B platform with 16MB DRAM. The A20B-3300-0312 uses the standard Intel Pentium. The A20B-3300-0602 uses the Intel Pentium MMX — with doubled L1 cache (8KB→16KB data, 8KB→16KB instruction), improved branch prediction, and MMX instructions. The Pentium MMX delivers noticeably better cache-dependent workload performance on the same clock frequency.

Q2: Is A20B-3300-0602 compatible with Series 16i-B or 18i-B, or is it exclusive to 21i-B?

A20B-3300-0602 is specified for Series 21i-B. The 16i-B and 18i-B platforms use A20B-3300-0600 (Pentium MMX 16MB). The three i-B CNC variants use different CPU module part numbers despite all using Pentium MMX processors — platform-specific connector or signal requirements determine which module fits which CNC.

Q3: Does replacing A20B-3300-0602 with A20B-3300-0603 (32MB) provide a performance benefit?

The additional DRAM in A20B-3300-0603 provides more working memory for the CNC processor. This is beneficial when the 21i-B is running larger programmes, more installed software options, or advanced GUI functions that consume additional memory. For standard configurations, 16MB is sufficient. The 32MB module benefits heavily-optioned 21i-B systems.

Q4: Does replacing A20B-3300-0602 affect CNC parameters or programmes?

No. Parameters and programmes reside in SRAM and FROM modules. Replacing the CPU module does not affect stored data. After fitting A20B-3300-0602, the CNC boots from FROM and reads parameters from SRAM.

Q5: Can A20B-3300-0602 replace an older 486-class CPU module in a 21i-B system?

The 21i-B's supported CPU modules are defined by the platform's main board socket specification. If the main board accepts Pentium MMX modules (A20B-3300-0602), the older 486-class modules served a different platform generation. The 21i-B's main board is matched to Pentium-class modules — confirm from the hardware documentation.